The present invention relates to semiconductor devices and methods of manufacturing the semiconductor devices.
As earlier semiconductor devices such as insulating gate bipolar transistors (IGBTs), the structure encompassing an n-type semiconductor region at the corner portion in the periphery of a semiconductor device is known, the corner portion is implemented by island-, wedge-, or layer-formed p-type floating regions, to improve the breakdown voltage at the corner portion (see JP2002-503401A1). There is another known structure in which an n-type semiconductor layer includes a p-type buried layer having an elliptic cross-sectional shape for improvements in breakdown voltage, turn-on speed, and the like (see JP2001-313393A).
Semiconductor chips of earlier IGBTs are being increasingly thinned in order to decrease on-state-voltage and turn-off power loss. However, the thinning of semiconductor chips is limited by restrictions of manufacturing processes. Therefore, the decrease of the turn-off power loss without increasing the on-state-voltage is difficult.
In the light of the aforementioned problems, an object of the present invention is to provide a semiconductor device having a decreased turn-off power loss with a smaller on-state-voltage, and to provide a method of manufacturing the semiconductor device having the same performances.